Spectrum sharing with switching of tier levels between networks and/or devices

ABSTRACT

Tier switching of spectrum access priority tier levels for networks in a multi-tier level spectrum access system is disclosed. The tier switching may be based on conditions in the networks to allow more efficient network/system operation. In an implementation, the switching of tier levels may be a swap of tier levels between a network/device and another network/device. In this case, the tier level of a network/device is switched or swapped with the tier level of another network/device and each network device operates at the tier level of the other network/device. In another implementation, the switching of tier levels may be a switching of tier levels used by a single network or a single device without any swap occurring with another network or device. In this case, the tier level of a network or device may be switched to another tier level for operation in the SAS.

BACKGROUND

Various types of wireless networks that utilize channels in frequencyspectrum that is shared with other networks have been proposed. Thesharing of frequency spectrum allows a wireless network to increasesystem bandwidth efficiency when channels in the shared frequencyspectrum are available for use by the wireless network. In variousconfigurations of these networks, the shared frequency spectrum may bespectrum in unlicensed frequency bands or spectrum in licensed orallocated frequency bands that are shared between licensed networks, forexample, on a prioritization basis. The prioritization may beimplemented on a tier level basis, in which different levels of priorityfor use of the frequency spectrum are assigned to different networks.These networks may include networks configured for use with differentmarket segments. For example, the networks that share frequency spectrummay each be configured for Department of Defense (DOD) users, policedepartment users, or cellular users. The networks may also be configuredfor the same market segment. For example, the networks that sharefrequency spectrum may each be configured as a corporate network.

An example of networks utilizing shared frequency spectrum isillustrated by a Dynamic Spectrum Access (DSA) system that includesmultiple base stations/networks that operate independent of one anotherto share an allocated frequency spectrum. A DSA system typicallyincludes an incumbent frequency spectrum user that has highest priorityfor spectrum access. A DSA system is typically configured so that thebase stations/networks within the DSA system use channels in a frequencyspectrum that is shared with other base stations/networks of the DSAsystem. The sharing of the frequency spectrum in the DSA system may bedone under the coordination of a controller that manages a channelassignment database. Various groups in the wireless industry arecurrently working to standardize operating rules for DSA systems thathave multiple tier levels of priority for spectrum access. In thesesystems, each base station/network in the DSA system may be assigned oneof the multiple tier levels of priority. A DSA database system enablingmultiple tier levels of priority is commonly known as a spectrum accesssystem (SAS).

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to exclusively or exhaustivelyidentify key features or essential features of the claimed subjectmatter. Nor is it intended as an aid in determining the scope of theclaimed subject matter.

The systems, methods, and apparatus of the embodiments provide tierlevel switching for networks in a spectrum access system in whichdifferent tier levels assigned to the networks define priority for useof frequency spectrum. The control and initiation of tier levelswitching between or within the networks of the spectrum access systemallows efficient utilization of spectrum in the networks of the spectrumaccess system.

In an implementation, a controller may be implemented in a spectrumaccess system that includes a first and a second network, and has aplurality of tier levels each indicating priority for spectrum access.The controller may assign one or more first channels to the firstnetwork based on the first network being assigned a first tier level ofthe plurality of tier levels and assign one or more second channels tothe second network based on the second network being assigned a secondtier level of the plurality of tier levels. The second tier level may bea higher priority level than the first tier level. As the networksoperate, the controller may determine that a tier switch is to takeplace between the first network and the second network. In response tothe determination that the tier switch is to take place, the controllermay initiate the tier switch between the first network and the secondnetwork, assign one or more third channels to the second network basedon the second network being assigned the first tier level, and assignone or more fourth channels to the first network based on the firstnetwork being assigned the second tier level. In an example, thecontroller may determine that the tier level switch is to take placebased on a tier switch request received by the controller from the firstnetwork. In another example, the controller may send a tier switchrequest received from the first network to the second network and thecontroller may determine that the tier switch is to take place based ona response to the tier switch request received by the controller fromthe second network.

In another implementation, a controller may be implemented in a networkof a spectrum access system that has a plurality of tier levels thateach indicates a priority for spectrum access. The controller mayreceive an assignment of at least one first channel based on the networkbeing assigned a first tier level of the plurality of tier levels by thespectrum access system, monitor a parameter in the network, determinethat a switch to a second tier level of the plurality of tier levels isto take place based at least on the parameter, send an indication to thespectrum access system that the network is switching to the second tierlevel of the plurality of tier levels, and receive an assignment of atleast one second channel based on the network being assigned the secondtier level of the plurality of tier levels by the spectrum accesssystem. In an example, the controller may determine that the switch tothe second tier level of the plurality of tier levels is to take placebased at least on the monitored parameter and a cost function. Theparameter may be monitored on a selected channel of the at least onefirst channel. The second tier level may be a higher priority level thanthe first tier level and the cost function may indicate a cost incurredby the network for operating at the second tier level. For example, thecost may comprise an additional billing cost for operators and/or usersof the network.

In another implementation, a controller may be implemented in a networkof a spectrum access system having at least a first tier level and asecond tier level of priority for spectrum access. The network in whichthe controller is implemented may be a network that is authorized tooperate at both the first tier level and the second tier level. Thecontroller may be configured to control one or more devices, for exampleaccess points or base stations, operating in the network. The controllermay receive an assignment of at least one first channel from thespectrum access system and assign the at least one first channel to atleast one first device based on the at least one first device beingassigned the first tier level by the controller. The controller may alsoreceive an assignment of at least one second channel from the spectrumaccess system and assign the at least one second channel to at least onesecond device based on the at least one second device being assigned thesecond tier level by the controller. During network operation, thecontroller may determine that a tier switch between the at least onefirst device and the at least one second device is triggered, initiatethe tier switch between the at least one first device and at least onesecond device, and assign the at least one second channel to the atleast one first device and the at least one first channel to the atleast one second device. The priority of the second tier level may behigher than the priority of the first tier level. The controller maydetermine that the tier switch between the at least one first device andthe at least one second device is triggered by determining that qualityof the at least one first channel used by the at least one first deviceis degraded below a threshold amount.

In a further implementation a controller may be implemented in aspectrum access system that includes a plurality of networks and has atleast first and second tier levels of priority for spectrum access. Thecontroller may receive information from a first network indicating thatfirst tier level spectrum is available for use by one or more secondnetworks and send the information on the first tier level spectrum tothe one or more second networks. In response to the receipt of theinformation at the one or more second networks, the controller mayreceive at least one response from the one or more second networks,process the at least one response, and initiate a tier switch for thefirst tier level spectrum by assigning one or more channels of the firsttier level spectrum from the first network to a selected network of theone or more second networks based on the at least one response. Theinformation on the first tier level spectrum may include conditions ofuse for the first tier level spectrum. The conditions of use may includea cost condition and the at least one response may indicate that theselected network of the one or more second networks meets the costcondition. In an example, the selected network may satisfy the costcondition by responding to the controller with a highest proposedpayment as compared to proposed payments received from other networks ofthe one or more second networks. In another example, the selectednetwork may satisfy the cost condition by agreeing to pay a set costdefined in the cost condition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example spectrum access systemincluding networks having devices configured to operate according to animplementation;

FIGS. 2A-2C are diagrams illustrating portions of example controllers ina spectrum access system;

FIGS. 3A-3C illustrate operations performed during a tier switch betweena first network and a second network in a spectrum access system;

FIG. 4 is a flow diagram illustrating operations performed by an examplenetwork controller when switching network tier levels in a spectrumaccess system;

FIG. 5A is a flow diagram illustrating operations performed by anexample spectrum access system controller when switching tier levels toutilize available spectrum in a spectrum access system;

FIG. 5B is a flow diagram illustrating operations performed by anexample network controller when switching tier levels to utilizeavailable spectrum in a spectrum access system;

FIG. 6A is a diagram illustrating an example network having devicesconfigured to switch between spectrum access system tier levels withinthe network;

FIG. 6B is a flow diagram illustrating operations performed by anexample network controller when switching devices between spectrumaccess system tier levels within a network;

FIG. 7 is a simplified block diagram showing an example networkcontroller; and,

FIG. 8 is a simplified block diagram showing an example spectrum accesssystem controller.

DETAILED DESCRIPTION

The system, method and apparatus will now be described by use of exampleembodiments. The example embodiments are presented in this disclosurefor illustrative purposes, and not intended to be restrictive orlimiting on the scope of the disclosure or the claims presented herein.

The methods, systems, and apparatus of the embodiments provide tierlevel switching between or within networks/devices in a spectrum accesssystem (SAS) in which the networks/devices are assigned tier levels thatindicate priority for spectrum access. An SAS of this type may be amulti-tier level system, for example, a 3-tier level priority systemthat includes spectrum users (networks and/or devices) that are eachassigned one of three priority levels for use of channels within theshared spectrum. As used in this disclosure, the term channel means aportion or a band of frequency spectrum within which a network/devicemay transmit and/or receive signals. For example, a channel assignmentto a network/device may comprise the assignment of one or more portionsor bands of frequency spectrum within which the network/device maytransmit and receive signals. The network/device may transmit andreceive using any technology on frequency channels within the one ormore portions or bands of frequency spectrum. In some implementations,the channel assignment may include channel numbers defined by aparticular wireless standard.

The three priority levels of a SAS 3-tier level system may include atier-1 level that includes incumbent spectrum users, a tier-2 level thatincludes spectrum users who are each licensed to use a certain portionof spectrum, and a tier-3 level that includes spectrum users who aregeneral allowed access (GAA) users. In the 3-tier level system, when atier-1 level user is active on a channel x, proximity tier-2 level andtier-3 level users cannot use the same channel x. In the absence of anactive tier-1 level user on a channel x, a tier-2 level user can use thechannel x. In the case where a tier-2 level user is using channel x, atier-3 level user cannot use channel x. A tier-3 level user can only usechannel x if there are no active tier-1 level or tier-2 level users onchannel x.

Spectrum access management in a 3-tier level SAS is accomplished byusing a SAS controller to manage an SAS channel assignment database. Ina 3-tier level SAS, since tier-1 level devices are the incumbents andhave highest priority in the spectrum for which they are incumbent, atier-1 level user does not need to request a channel assignment from thecontroller of the SAS channel assignment database. The tier-1 levelusers may use the spectrum for which they are incumbent based on theirown decisions, independently of the controller. Tier-1 level users mayor may not inform (register with) the controller of the SAS channelassignment database to inform the SAS controller of the channels beingused by the tier-1 level users. Whether or not a tier-1 level userinforms the controller of its channel use depends on the systemconfiguration. For example, if a tier-1 level user is a department ofdefense (DOD) or Military related entity, the tier-1 level user may notwant to inform the controller of its channel usage for security reasons.In other cases, a spectrum access system operator may have agreementswith tier-1 level users that the tier-1 level users will register theirchannel usage with the controller. In these cases, the registration ofchannel usage by tier-1 level users may allow the SAS controller to moreefficiently manage channel assignments to tier-2 level and tier-3 levelusers.

In a 3-tier level SAS, tier-2 level and tier-3 level users send databasequeries to request channel assignments from the SAS controller in orderto use spectrum in the SAS. The database queries allow the SAScontroller to register the tier-2 level and tier-3 level users in an SASdatabase in order to manage and coordinate the spectrum usage accordingto a set of rules that avoids channel conflicts and interference.

Implementations of this disclosure provide technical advantages insystems such as a multi-tier level SAS by allowing the networks ordevices operating in the multi-tier level SAS to switch tier levels. Inan implementation, the switching of tier levels may be a swap of tierlevels between a network/device and another network/device. In thiscase, the tier level of a network/device is switched or swapped with thetier level of another network/device and each network device operates atthe tier level of the other network/device after the tier switch. Inanother implementation, the switching of tier levels may be a switchingof tier levels used by a single network or a single device without anyswap occurring with another network or device. In this case, the tierlevel of a network or device may be switched to another tier level foroperation in the SAS.

In one example, an implementation provides advantages in a SAS byallowing a first network having low priority tier level to temporarilyswitch tier levels with a second network having a high priority tierlevel. The tier level switch may take place during a time period whenthe channel quality and/or bandwidth provided to the first network atthe low priority level is degraded and the second network is not fullyutilizing, or doesn't require, the channel quality and/or bandwidthavailable to the second network at the high priority level. In thiscase, the tier switch allows the first network to utilize the higherchannel quality and/or bandwidth available at the high priority levelwhen the higher channel quality and/or bandwidth are not needed by thesecond network.

In another example, an implementation provides advantages by allowing anetwork to self-initiate the switching of tier levels at which thenetwork operates based on channel quality and/or bandwidth in thenetwork and a cost function that indicates a cost of switching tierlevels. The cost may be additional charges incurred by the network tooperate at a higher tier level. When channel quality and/or bandwidthneed improvement and the cost function indicates the cost is acceptable,the network may inform the spectrum access system that the network isswitching tier levels and initiate operation at the higher tier level.The tier switch allows the network to utilize the higher channel qualityand/or bandwidth available at the higher priority level. In this case,the tier switch may allow a network to operate in a spectrum accesssystem while trading off the lower cost of operating at a low tier levelwith the higher cost of operating at the higher tier level for betterquality service.

In a further example, another implementation provides advantages byallowing a first network operating at the first tier level and havingavailable spectrum at the first tier level that is not being utilized toshare the available spectrum with one or more second networks. In thisexample, a network controller in the first network having the availablespectrum may provide information on the available spectrum to a SAScontroller of a spectrum access system. The SAS controller may thenbroadcast the information to one or more second networks of the spectrumaccess system and coordinate a tier switch between the first network anda selected network of the one or more second networks. The tier switchallows the selected network to utilize the excess spectrum of the firstnetwork at the first tier level. The coordination of the tier switch bythe network controller may involve determining that the selected networkmeets a condition of use included in the information provided by thefirst network. In an example, the conditions of use may include a costcondition and the coordination of the tier switch may includedetermining that the selected network of the one or more second networksmeets the cost condition. In an example, the selected network may meetthe cost condition by responding to the controller with a highestproposed payment or bid to be credited to the first network for use ofthe first tier level spectrum as compared to proposed payments receivedfrom other networks. In another example, the selected network may meetthe cost condition by agreeing to a set payment of a cost set out in thecost condition. The payment may be credited an account associated withthe first network by the SAS controller.

The implementations have applicability to systems such as Wi-Fi systemsor long term evolution-unlicensed (LTE-U) systems, systems utilizingfrequency spectrum in the television white space (TVWS), dynamicspectrum access (DSA) systems, and any other systems in which frequencyspectrum is shared based on assignment of tier levels for priority ofaccess to spectrum.

FIG. 1 shows a spectrum access system 100 that includes three networks.Network A includes devices 114, 116, 118, and 120, and network Acontroller 103. Network B includes devices 122, 124, 126, and 128, andnetwork B controller 102. Network C includes devices 132 and 134, andnetwork C controller 106 that includes high power access point 130.Devices 122 and 126 may be base stations configured as cellular basestations and devices 124 and 128 may be mobile handsets or similardevices operating in a cellular network comprising network B. Devices114 and 118 may be base stations configured as wireless access nodes(functioning as base stations or access points) for a private/publicservice network comprising network A, and devices 116 and 120 may betablet computers or similar devices operating in the private/publicservice network A. Device 132 may be a base station configured as aWi-Fi access point of a business/organizational local area network (LAN)comprising network C, and device 134 may be a laptop computer or similardevice operating in the LAN network. FIG. 1 also shows system 101 thatincludes network X controller 108, base station 110 and mobile handset112. System 101 may be located remotely from networks A, B, and C andmay be a spectrum access system that is different from, and independentof, spectrum access system 100. Network A controller 103, network Bcontroller 102, and network C controller 106 are each showncommunicating with a SAS controller 104 of spectrum access system 100.SAS controller 104 includes a spectrum access system (SAS) database.While devices 116, 120, 124, 128, and 134 are shown as particular typesof mobile devices, in other implementations each of these devices may beconfigured as any other type of wireless device, such as a mobile phone,a laptop, a tablet device, a gaming/media device, a personal computer,or any other type of wireless device. Also, while devices 114, 118, 122,126, and 132 are shown as particular types of base stations, in otherimplementations each of these devices may be implemented as any othertype of base station, access point, transmitter station, or other typeof apparatus/device that provides a communications interface between anetwork and a wireless device.

Networks A, B, and C of spectrum access system 100 may each be assignedto a tier level of 3 available tier levels of spectrum access system100. In an implementation, devices (nodes) 114 and 118 of network A maybe assigned to tier-1 level (highest priority), devices (base stations)122 and 126 of network B may be assigned to tier-2 level (mediumpriority), and device (access point) 132 of network C may be assigned totier-3 level (lowest priority). Tier-1 users/networks may be in thecategory of high priority users such as radar systems and Department ofDefense (DoD) users. Tier-2 users/networks may be in the category ofintermediate priority users such as police departments, firedepartments, or licensed cellular systems. Tier-3 users/networks may bein the category of other users with general allowed access. For example,tier-3 users may be local access networks (LANs) of businesses or otherorganizations.

In the 3-tier spectrum access system 100, when a tier-1 user (network orbase station) is active on a channel x, proximity tier-2 and tier-3users cannot use the same channel x. In the absence of an active tier-1user on a channel x, a tier-2 user can use the channel x. In this case,a tier-3 channel cannot use channel x. A tier-3 user can only usechannel x if there are no active tier-1 and tier-2 users on channel x.The overall management of spectrum access system 100 according to theserules is performed by SAS controller 104.

In an implementation of spectrum access system 100, each of the tier-2level and tier-3 level network controllers may send queries for channelassignment on behalf of the devices in their network and allocate theassigned channels to the individual devices in the network. For example,network B controller 102 may send a query to SAS controller 104 forchannel assignments for network B. When SAS controller 104 responds withchannel assignments based on network B having a tier-2 level priorityand the location of network B, network B controller may then allocatethe channels assigned to network B to the individual base stations 122and 126. Network C controller 106 may send a query to SAS controller 104for channel assignments for network C. When SAS controller 104 respondswith channel assignments based on network C having a tier-3 levelpriority and the location of network C, network C controller may thenallocate the channels assigned to network C to the access point 132.

In another implementation of FIG. 1, each of the tier-2 level basestations 122 and 126 of network B may be implemented to send a query fora channel assignment to SAS controller 104 through network B controller102. SAS controller 104 responds to the query by sending a channelassignment of one or more channels directly to each base station 122 and126 based on Network B having tier-2 level priority and the locations ofbase stations 122 and 126. Also, tier-3 level access point 132 ofnetwork C may send a query for a channel assignment to SAS controller104 through high power access point 130 and network C controller 106.SAS controller 104 responds to the query by sending a channel assignmentof one or more channels directly to access point 132 based on network Chaving tier-3 level priority and on the location of access point 132.

Access nodes 114 and 118 of network A are tier-1 level devices that havea highest priority for use of designated spectrum that is within thespectrum usable in spectrum access system 100. Access nodes 114 and 118may use the designated spectrum for communication with tablet computingdevices 116 and 120 without permission or assignment from SAS controller104. In the implementation of FIG. 1, access nodes 114 and 118 may sendinformation through network A controller 103 to SAS controller 104 thatinforms SAS controller 104 of channels that are being used in network A.SAS controller 104 may then use the information received from nodes 114and 118 when assigning channels to tier-2 and tier-3 level devices innetwork B and network C.

FIGS. 2A-2C are diagrams illustrating portions of example controllers ina shared frequency spectrum system. FIG. 2A shows functional portions ofnetwork C controller 106 of FIG. 1. Network C controller 106 may includeprocessor 220, access point interface 216, network interface 219,channel/network parameter monitor 222, channel assignment manager 218,and tier switch timer 224. Access point interface 216 may include highpower access point/transceiver 130 that allows network C controller 106to communicate with access point 132 over a wireless interface. FIG. 2Bshows functional portions of network B controller 102 of FIG. 1. NetworkB controller 102 may include processor 206, base station interface 202,network interface 208, channel/network parameter monitor 210, channelassignment manager 204, and tier switch timer 212. FIG. 2C showsfunctional portions of SAS controller 104 of FIG. 1. SAS controller 104may include processor 234, network interface 228, channel assignmentdatabase 230, network subscription database 236, network tier database232, and tier switch manager/database 226. The operations of theportions of network A controller 103, network B controller 102, and SAScontroller 104 in various implementations of FIG. 1 may be explained inrelation to the flow diagrams of FIGS. 3A-3C, FIG. 4, and FIGS. 5A-5B.

FIGS. 3A-3C illustrate example operations performed during a tier switchbetween a first network and a second network in a spectrum accesssystem. FIGS. 3A-3C show an implementation of spectrum access system 100in which network C controller 106 and a network B controller 102communicate with SAS controller 104 of spectrum access system 100 toperform a tier level switch between network C and network B.

FIG. 3A illustrates example operations performed by network C controller106 as network C controller 106 interacts with SAS controller 104 inspectrum access system 100 during a tier level switch between network Cand network B.

The process begins at 302 where network C controller 106 initiatesoperation at the tier-3 level in spectrum access system 100. To initiateoperation at the tier-3 level, processor 220 of network C controller 106may send a database query to SAS controller 104 requesting a channelassignment as a tier-3 level network. Processor 220 of network Ccontroller 106 may control channel assignment manager 218 to configurethe database query and send the database query through network interface219 over link 214 to SAS controller 104. Network C controller 106 thenreceives a query response from SAS controller 104 at network interface219 on link 214 that includes a channel assignment identifying channelsthat SAS controller 104 has assigned to network C as a tier-3 levelnetwork. Channel assignment manager 218 processes the channel assignmentand stores the identity of the assigned channels in a channel assignmentdatabase. Processor 220 then controls channel assignment manager 218 tocommunicate with access point 132 through access point interface 216 toallocate channels to access point 132.

At 304, access point 132 operates on one or more of the channelsassigned to network C as a tier-3 level device. In the example of FIG.3A, at least one uplink channel and at least one downlink channel may beassigned by network C controller 106 for communications between accesspoint 132 and device 134. During the operation of network C, accesspoint 132 and/or device 134 monitor channel parameters on the assignedchannels on which access point 132 and device 134 communicate with oneanother. In monitoring the channel parameters, access point 132 maysample a signal on at least one channel from device 134 on the uplinkand device 134 may sample a signal on at least one channel from accesspoint 132 on the downlink. During the monitoring, access point 132 maygenerate N parameter samples (S₁ . . . S_(N)) for each at least onechannel on the uplink, and device 134 may generates N parameter samples(S₁, SN) for each at least one channel on the downlink. The samples maybe normally uniform samples and the number of samples may be fixed.Access point 132 and/or device 134 may send the series of N parametersamples for the at least one channel to network C controller 106 atselected times. Network C controller 106 receives the N parametersamples at access point interface 216 on link 237 and the N parametersamples are provided to channel/network parameter monitor 222. In animplementation, the N parameter samples may comprise power levelmeasurements of interference on the assigned channels. In otherimplementations, the N parameter samples may comprise any other type ofmeasurements on the selected channel such as bit error rate/packet errorrate, channel throughput, or other quality of services (QoS) relatedparameters.

At 306, as network C operates as a tier-3 level network, network Ccontroller 106 determines if a tier switch is needed. The determinationat 306 may be performed, for example, periodically. In animplementation, processor 220 may control channel/network parametermonitor 222 to determine a metric n using the N samples (S₁, . . .S_(N)) that were received from access point 132 and/or device 134 bychannel/network parameter monitor 222 during the channel monitoring timeperiod. The metric n may comprise a power measurement determined fromthe N samples that indicates a level of interference as measured byaccess point 132 or device 134 on the uplink or downlink, respectively.The metric for the selected channel may be determined from the samplesas the value n, where n is represented by:

$n = {\frac{1}{N}{\sum\limits_{i = 1}^{N}\; {S_{i}}^{2}}}$

To determine if a tier switch is needed processor 220 may determine ifn>n_(threshold) for the selected channel, where n_(threshold) is set ata threshold level of interference that triggers a tier switch. In otherimplementations, the metric used to determine if a tier switch is neededmay comprise any other type of metric that may be associated withquality of service in network C, such as bit error rate/packet errorrate, channel throughput, network throughput or other quality ofservices (QoS) related parameters.

If, at 306, it is determined that a tier switch is not needed theprocess moves back to 304 and network C controller 106 continues tooperate network C as a tier-3 network. If, at 306, is it determined thata tier switch is needed the process moves to 308.

At 308, network C controller 106 generates a tier switch request. Thetier switch request may include information associated with a desiredtier level into which network C requests to switch. The tier switchrequest may also include information associated with an amount ofspectrum or range of frequencies that is to be included in the tierswitch, and a time period for which the tier switch is requested tolast. Processor 220 may generate the tier switch request and initiatesending of the tier switch request to SAS controller 104 over link 214through network interface 219.

At 310, network C controller 106 receives a response to the tier switchrequest from SAS controller 104. Processor 220 may receive the responseto the tier switch request from SAS controller 104 at network interface219 over link 214. The response to the tier switch request may includean indication that SAS controller 104 is able to perform the tierswitch.

At 312, processor 220 determines if the response to the tier requestconfirms that the tier switch is to take place. If the response to thetier switch request indicates that SAS controller 104 accepts the tierswitch request, the tier switch is confirmed and the process moves to314. Alternatively, at 312, if the response to the tier switch requestindicates SAS controller 104 rejects the tier switch request, the tierswitch is not confirmed and the process moves back to 304. At 304,network C controller 106 continues to operate network C as a tier-3network.

At 314, network C controller 106 initiates tier-2 level operation.Processor 220 of network C controller 106 may send a database query toSAS controller 104 requesting a channel assignment as a tier-2 network.Processor 220 of network C controller 106 may control channel assignmentmanager 218 to configure the database query and send the database querythrough network interface 219 over link 214 to SAS controller 104.Network C controller 106 then receives a query response at networkinterface 219 on link 214 that includes a channel assignment identifyingat least one channel that SAS controller 104 has assigned to network Cas a tier-2 level network. Channel assignment manager 218 processes thechannel assignment and stores the identity of the assigned channels in achannel assignment database. Processor 220 then controls channelassignment manager 218 to communicate with access point 132 to allocatechannels for use by access point 132. At 314, processor 220 may also settier switch timer 224 to run for the time period of the tier switch.

At 316, access point 132 then operates on one or more of the channelsassigned to network C as a tier-2 level device in the tier switch. At322, as network C operates as a tier-2 network, network C controllermonitors tier switch timer 224 to determine if the tier switch timeperiod is expired. If the tier switch timer 224 is not expired,processor 220 continues to control network C controller to operate as atier-2 network at 316. If the tier switch timer 224 is expired, theprocess moves to 302 where processor 220 terminates operation at thetier-2 level and initiates operation at the tier-3 level for network Cin spectrum access system 100.

FIG. 3B illustrates example operation performed by network B controller102 as network B controller 102 interacts with SAS controller 104 inspectrum access system 100 as a tier level switch between network C andnetwork B is performed. In an implementation, the process of FIG. 3B maybe performed concurrently with the performance of the process of FIG. 3Aby network C controller 106.

The process begins at 330 where network B controller 102 initiatesoperation at the tier-2 level in spectrum access system 100. To initiateoperation at the tier-2 level, processor 206 of network controller 102may initiate the sending of a database query to SAS controller 104requesting a channel assignment as a tier-2 network. Processor 206 ofnetwork B controller 102 may control channel assignment manager 204 toconfigure the database query and send the database query through networkinterface 208 over link 214 to SAS controller 104. Network B controller102 then receives a query response at network interface 208 on link 214that includes a channel assignment identifying channels that SAScontroller 104 has assigned to network B as a tier-2 level network.Channel assignment manager 204 processes the channel assignment andstores the identity of the assigned channels in a channel assignmentdatabase. Processor 206 then controls channel assignment manager 204 tocommunicate with base stations 122 and 126 to allocate channels for useby base stations 122 and 126.

At 332, base stations 122 and 126 operate on one or more of the channelsassigned to network B as tier-2 level devices.

At 334, as network B operates as a tier-2 network, network B controller102 determines if a tier switch query has been received from SAScontroller 104. The determination at 334 may be performed by processor206 monitoring communications received at network interface 208 on link214 from SAS controller 104. If a tier switch query has not beenreceived, the process returns to 332 and network B continues operationas a tier-2 network. If a tier switch query has been received theprocess moves to 336.

At 336, network B controller 102 initiates sending of a response to thetier switch query to SAS controller 104. In the example of FIG. 3B, theresponse may comprise an acceptance indicating to SAS controller 104that network B controller 102 is able to accept the tier switch.Processor 206 may determine that network B is able to accept the tierswitch based on information in the tier switch query that indicates thetier level and the amount of spectrum or range of frequencies that thenetwork requesting the tier switch has requested, and the time periodfor which the tier switch is requested to last. Information provided bychannel/network parameter monitor 210 may be considered in conjunctionwith the information in the tier switch query when making thedetermination. For example, processor 206 may determine that network Bhas spectrum which is unused and available in a large enough amount toallow it to accept the tier switch request. As part of determining if itmay accept the tier switch, processing 206 may also determine thatinterference conditions in network B on tier-2 and/or tier-3 channelsare at a low level and Network B devices could operate on tier-3channels without degradation. In one implementation, channel/networkparameter monitor 210 may monitor a parameter x during tier-2 operationin a process similar to the monitoring performed by network C controller106 when the parameter n is determined at operations 304 and 306 of FIG.3A. The monitoring of the parameter x may be performed on tier-3 and/ortier-2 channel frequencies. When interference conditions as indicated bythe parameter x in network B are good and network B has availablespectrum, network B may accept the tier switch.

At 338, network B controller 102 determines if a confirmation to theresponse comprising the acceptance of the tier switch is received fromSAS controller 104. If a confirmation is not received, the processreturns to 332 and network B continues to operate as a tier-2 network.If a confirmation is received, the process moves to 342.

At 342, network B controller 102 initiates operation as a tier-3network. The initiation of operation network B as a tier-3 network at342 may be performed similar to the initiation of the operation as atier-2 network at 330 with the exception that network B controller 102sends a database query to SAS controller 104 as a tier-3 network andnetwork B is assigned channels as a tier-3 network. At 342, processor206 may also set tier switch timer 212 to run for the time period of thetier switch. At 346, base stations 122 and 126 operate on one or more ofthe channels assigned to network B as a tier-3 level network.

At 348, as network B operates as a tier-3 network, network B controller102 determines if the tier switch time period has expired. Processor 206determines if the tier switch period has expired by monitoring tierswitch timer 212. If the tier switch period is not expired, processor206 continues to control network B controller to operate as a tier-3network at 346. If the tier switch period is expired, the process movesto 330 where processor 206 terminates operation at the tier-3 level andinitiates operation at the tier-2 level in spectrum access system 100.

FIG. 3C illustrates example operation performed by SAS controller 104 asSAS controller 104 interacts with network B controller 102 and network Ccontroller 106 in spectrum access system 100 as a tier level switchbetween network C and network B is performed. In an implementation, theprocess of FIG. 3C may be performed concurrently with the performance ofthe processes of FIG. 3A and FIG. 3B by network C controller 106 andnetwork B controller 102, respectively.

The process of FIG. 3C begins at 349 where SAS controller assignschannels to network B as a tier-2 level network and to network C as atier-3 level network. During operation at 349, processor 234 may receivedatabase queries from network B controller 102 and network C controller106 at network interface 228 over link 214. Processor 234 may theninteract with network tier database 232 and channel assignment database230 to assign channels from channel assignment database 230 to network Band network C. The channel assignments will be based on network C beingassigned tier-3 level and network B being assigned tier-2 level innetwork tier database 232. The channel assignments may be stored inchannel assignment database 230. Processor 214 then initiates thesending of the channel assignments to network B controller 102 andnetwork C controller 106 over link 214 through network interface 228.

At 350, as network C and network B operate as tier-3 and tier-2 levelnetworks, respectively. SAS controller 104 receives a tier switchrequest from network C controller 106 at network interface 228 on link214. Processor 234 receives the tier switch request and interacts withtier switch manager/database 226 to initiate processing of the tierswitch request. The tier switch request may include informationassociated with a desired tier level into which network C requests toswitch. The tier switch request may also include information associatedwith an amount of spectrum or range of frequencies that is to beincluded in the tier switch, and a time period for which the tier switchis requested.

At 352, SAS controller 104 determines a potential tier switch that maybe performed. Processor 234 may determine that network B is a candidatefor a tier switch with network C based on the information in the tierswitch request and information from tier switch manager/database 226.The information in tier switch manager/database 226 may include tierswitch information that is associated with other networks in SAS system100. For example, the information in tier switch manager/database 226may include information that indicates that network B will accept tierswitches with other networks. The information in tier switchmanager/database 226 may also include information on what tier levelsand spectrum/frequency ranges network B will switch to or from, andother information such as particular time periods during which network Bwill accept tier switches.

At 354, SAS controller 104 sends a tier switch query to network Bcontroller 102. Processor 234 initiates the sending of the tier switchquery through network interface 228 over link 214. The tier switch querymay include the information associated with a desired tier level intowhich network C requests to switch. The tier switch query may alsoinclude the information associated with an amount of spectrum or rangeof frequencies that is to be included in the tier switch, and the timeperiod for which the tier switch is requested.

At 356, SAS controller 104 receives a response from network B controller102. Processor 234 receives the response from network interface 228 and,at 358, determines whether the response indicates that network Bcontroller 102 has accepted the tier switch with network C. If the tierswitch has been accepted the process moves to 359. If the tier switchhas not been accepted the process ends.

At 359, SAS controller 104 initiates the tier switch between network Cand network B. Processor 234 initiates the sending of a response to thetier switch request to network C controller 106 indicating that the tierswitch is confirmed through network interface 228 over link 214. Theresponse sent to network C controller may include confirmation of thedesired tier level that network C requested. The response may alsoinclude confirmation of the amount of spectrum or range of frequenciesthat is to be included in the tier switch, and the time period for whichthe tier switch is requested. Processor 234 also may initiate thesending of a response to the tier switch acceptance received fromnetwork B controller 102 at 356 to confirm the tier switch throughnetwork interface 228 over link 214.

At 360, the tier switch is implemented as SAS controller 104 assignschannels to network B as a tier-3 level network and to network C as atier-3 level network. In order to implement the operation of 360,processor 234 may interact with network tier database 232 and channelassignment database 230 to create temporary assignments of network C tothe tier-2 level and network B to the tier-3 level. Then, duringoperation at 360, processor 234 may receive database queries fromnetwork B controller 102 and network C controller 106 at networkinterface 228 over link 214 and assign channels from channel assignmentdatabase 230 to network B and network C. The channel assignments will bebased on network C being assigned tier-2 level and network B beingassigned tier-3 level in network tier database 232. Processor 234 theninitiates the sending of the channel assignments to network B controller102 and network C controller 106 over link 214 through network interface228. The channel assignments used at 360 may be stored in network tierdatabase and channel assignment database 230 as temporary assignmentsthat are valid for the time period of the tier switch.

At 362, as SAS controller 104 assigns channels to network B as a tier-3level network and to network C as a tier-3 level network, SAS controller104 determines if the tier switch time period is expired. Processor 234may monitor a timer to perform the operation of 362. If the tier switchtime period is not expired, processor 234 controls SAS controller 104 tocontinue to assign channels to network B as a tier-3 level network andto network C as a tier-3 level network. If the tier switch period isexpired, the process moves to 364.

At 364, SAS controller 104 terminates the tier switch between network Band network C. Processor 234 may interact with network tier database 232to change the temporary assignment of tier-2 to network C back to anassignment of tier-3 to network C, and change the temporary assignmentof tier-3 to network B back to an assignment of tier-2 to network B, theprocess then moves to 349 where SAS controller assigns channels tonetwork B as a tier-2 level network and to network C as a tier-3 levelnetwork.

In other examples of the process shown in FIGS. 3A-3C, the tierswitching may take place between networks operating at any of the tierlevels of spectrum access system 100. For example, depending on thesituation, a network may request a tier switch to a lower prioritylevel, for example from tier-2 level to tier-3 level. In anotherexample, a first network operating at tier-2 or tier-3 level may requesta tier switch with a second network operating at tier-1 level. In thiscase, the first network would operate as a tier-1 level network intier-1 level spectrum after the tier switch and would not need toreceive channel assignments from the SAS controller, while the secondnetwork would operate as a tier-2 or tier-3 level network and need toreceive channel assignments during the period of the tier switch.

In other implementations, a network may switch the tier level that itoperates in by self-initiating a tier switch. In this case, the networkmay not switch tier levels with another network, but switch its own tierlevel independently of the tier levels that other networks in thespectrum access system use. The switching of tier levels may incur acost or credit to the network depending on the tier level switched into.For example, if the network switches to a higher priority tier level, acost may be incurred by the network and, if the network switches to alower priority tier level, a credit may be given to the network. In animplementation, SAS controller 104 may include functions for maintainingaccounting for tier switches of networks within spectrum access system100 in network subscription database 236.

FIG. 4 is a flow diagram illustrating operations performed by an examplenetwork controller when switching network tier levels in a spectrumaccess system. FIG. 4 may be explained using network C controller 106 ofFIGS. 1 and 2A as the controller of FIG. 4.

The process begins at 402 where network C controller 106 initiatesoperation at the tier-3 level in spectrum access system 100. To initiateoperation at the tier-3 level, processor 220 of network C controller 106may send a database query to SAS controller 104 requesting a channelassignment as a tier-3 network. Processor 220 of network C controller106 may control channel assignment manager 218 to configure the databasequery and send the database query through network interface 219 overlink 214 to SAS controller 104. Network C controller 106 then receives aquery response at network interface 219 on link 214 that includes achannel assignment identifying at least one channel that SAS controller104 has assigned to network C as a tier-3 level network. Channelassignment manager 218 processes the channel assignment and stores theidentity of the assigned channels in a channel assignment database.Processor 220 then controls channel assignment manager 218 tocommunicate with access point 132 through access point interface 216 toallocate channels to access point 132.

At 404, access point 132 operates on one or more of the channelsassigned to network C as a tier-3 level network. In the example of FIG.4, at least one uplink channel and at least one downlink channel may beassigned by network C controller 106 for communications between accesspoint 132 and device 134.

At 406, during the operation of network C, access point 132 and/ordevice 134 monitor channel parameters on the assigned channels on whichaccess point 132 and device 134 communicate with one another. Inmonitoring the channel parameters, access point 132 may sample a signalon at least one channel from device 134 on the uplink, and device 134may sample a signal on at least one channel from access point 132 on thedownlink. During the monitoring, access point 132 may generate Nparameter samples (S1 . . . SN) for each at least one channel on theuplink, and device 134 may generates N parameter samples (S1 . . . SN)for each at least channel on the downlink. The samples may be normallyuniform samples and the number of samples may be fixed. Access point 132and/or device 134 may send the series of N parameter samples for the atleast one channel to network C controller at selected times. Network Ccontroller 106 receives the N parameter samples at access pointinterface 216 on link 237 and the N parameter samples are provided tochannel/network parameter monitor 222. In an implementation, the Nparameter samples may comprise power level measurements of interferenceon the assigned channels. In other implementations, the N parametersamples may comprise any other type of measurements such as bit errorrate/packet error rate, channel throughput, or other quality of services(QoS) related parameters. In further implementations, the N parametersamples may comprise network parameters such as throughput measurements.

At 408, as network C operates as a tier-3 network, network C controller106 determines if a tier switch is needed. The determination at 408 maybe performed, for example, periodically. Processor 220 controlschannel/network parameter monitor 222 to determine a metric n using theN samples (S1, . . . SN) for the selected channel that were received bychannel/network parameter monitor 222 during the channel monitoring timeperiod. In an implementation, the metric n may comprise a powermeasurement determined from the N samples that indicates a level ofinterference on the selected channel as measured by access point 132 ordevice 134 on the uplink or downlink, respectively. The metric for theselected channel may be determined from the samples as a value n, wheren is represented by

$n = {\frac{1}{N}{\sum\limits_{i = 1}^{N}\; {S_{i}}^{2}}}$

To determine if a tier switch is needed processor 220 may determine ifn>n_(threshold) for the selected channel, where n_(threshold) is set ata threshold level of interference.

In other implementations, the metric used to determine if a tier switchis needed may comprise any other type of metric that may be associatedwith quality of service in network C, such as bit error rate/packeterror rate, channel throughput, network throughput or other quality ofservices (QoS) related parameters.

If, at 408, it is determined that a tier switch is not needed theprocess moves back to 404 and 406 where network C controller 106continues to operate network C as a tier-3 level network. Network Ccontroller 106 will also continue to monitor parameters on the assignedchannels. If, at 408, is it determined that a tier switch is needed theprocess moves to 410.

At 410, processor 220 analyzes the tier switch in view of factorsincluding the value of n, network/device requirements, and a costfunction. In the operation of 410, processor 220 analyzes whether thebenefits of making a switch from the tier-3 level to the tier-2 leveloutweigh the cost as defined by the cost function. The cost function maybe a function provided by the spectrum access network and stored networkC controller 106. For example, SAS controller 104 may send an updatedcost function to network controllers in spectrum access systemperiodically. SAS controller 104 may also send an updated cost functionto the network controllers as conditions change in spectrum accesssystem 100. The cost function may define a cost to the operators and/orusers of network C that will be incurred if a tier switch to the tier-2level is made based on conditions of the tier switch. For example, thecost function may define the cost of a tier switch to tier-2 based on atime of time of day that the tier switch takes place and the duration ofthe tier switch. Processor 220 may also include information/data onvarious thresholds defined for network C when determining whether a tierswitch should be performed. For example, a higher level of cost for atier switch may be accepted for higher levels of interference asindicated by the value of the parameter n. In another example, a higherlevel of cost for a tier switch may be accepted for a given level ofinterference, as indicated by the parameter n, when higher than normalquality level transmissions, for example high quality videotransmissions, are required in network C.

At 412, processor 220 determines if the tier switch is confirmed basedon the analysis of operation 410. If the analysis determines that thecost of the tier switch is not acceptable, the process moves back to 404where network C continues to operate as a tier-3 network. If theanalysis determines that the cost of the tier switch is acceptable, thetier switch is confirmed and the process moves to 414.

At 414, network C controller 106 sends an indication of the tier switchof network C to tier-2 to SAS controller 104. The indication may includea database query requesting channel assignments for network C as atier-2 network. Processor 220 of network C controller 102 may controlchannel assignment manager 204 to configure the database query and sendthe database query through network interface 219 over link 214 to SAScontroller 104.

At 416, SAS controller 104 assigns channels to network C as a tier-2level network. In order to implement the operation of 416, processor 234of SAS controller 104 may interact with network tier database 232 andchannel assignment database 230 to create a temporary assignment ofnetwork C to the tier-2 level. During operation at 360, processor 234may receive database query from network C controller 106 at networkinterface 228 over link 214 and assign channels from channel assignmentdatabase 230 to network C. The channel assignments will be based onnetwork C being assigned tier-2 in network tier database 232. Processor214 then initiates the sending of the channel assignments to network Ccontroller 106 over link 214 through network interface 228. The channelassignments may be stored in network tier database 232 and channelassignment database 230 as temporary assignments that are valid for thetime period of the tier switch.

At 418, Network C controller 106 receives a response to the indicationof the tier switch at network interface 219 on link 214. The responseincludes a channel assignment identifying at least one channel that SAScontroller 104 has assigned to network C as a tier-2 level network.Channel assignment manager 218 processes the channel assignment andstores the identity of the assigned channels in a channel assignmentdatabase. Processor 220 then controls channel assignment manager 218 tocommunicate with access point 132 through access point interface 216over link 237 to allocate channels for use by access point 132.

At 420, access point 132 then operates on one or more of the channelsassigned to network C as a tier-2 level device in the tier switch. Asnetwork C operates as a tier-2 network, processor 220 of network Ccontroller 106 may monitor switch timer 212 to determine if the tierswitch period has expired. When the tier switch period expires, theprocess moves back to 402 where network C controller 106 terminatesoperation at the tier-2 level and initiates operation of network C atthe tier-3 level in spectrum access system 100.

FIGS. 5A and 5B illustrate operations of a process in which tierswitching may be performed to allow spectrum of a spectrum access systemto be utilized when the spectrum would be otherwise unutilized and/orunavailable for use. FIGS. 5A and 5B show an implementation of spectrumaccess system 100 in which network B controller 102 and network Ccontroller 106 communicate with SAS controller 104 of spectrum accesssystem 100 to perform a tier switch for network C that allows network Cto utilize spectrum that is unutilized in network B.

FIG. 5A is a flow diagram illustrating operations performed by anexample system controller when switching tier levels to utilizeavailable spectrum in a spectrum access system. FIG. 5A may be explainedusing SAS controller 104 and network B controller 102 of FIGS. 1 and 2Aas the network B controller and SAS controller, respectively, of FIG.5A.

The process begins at 502 where network B controller 102 determines thatnetwork B has excess spectrum available at the tier-2 level and sends anindication of the availability to SAS controller 104. For example,network B controller 102 may determine that network B has been assignedtier-2 level channels that are not being utilized by network B devicesand send an indication of this to SAS controller 104. The determinationat 502 may be made on a time period basis. For example, thedetermination at 502 may be a determination that the spectrum isunderutilized during a certain time of day. Processor 206 may make thedetermination by monitoring the use of channels assigned to network B bySAS controller 104 and stored in channel assignment database. When thenumber of unused channels as indicated by channel assignment manager 204is above a designated amount, the spectrum comprising the channel may beconsidered underutilized. For example, processor 206 may determine thatthe number of unused channels indicated by channel assignment manager204 is above the designated amount each day between the times of 1 amand 4 am. In this case, processor 206 may make a determination that ithas excess spectrum tier-2 level available between 1 am and 4 pm eachday and send an indication of this availability to SAS controller 104through network interface 208 over link 214. In other examples, thedetermination may also be made on a current basis, where thedetermination is a determination that spectrum is presently beingunderutilized. This determination may include a determination that theunderutilization has continued for the duration of a certain time periodand is likely to continue. In this case, processor 206 may make adetermination that it has excess spectrum tier-2 level that is presentlyavailable and will be available for some time period into the future,and send an indication of this availability to SAS controller 104through network interface 208 over link 214. The indication ofavailability sent to SAS controller 104 at 502 may also includeconditions of use. For example, the conditions of use may include a costcondition indicating that network 13 will grant the tier switch to anetwork responding with a highest bid for the available spectrum. Inthis case network B will switch the available spectrum with the networkresponding with a highest proposed payment or bid to be credited tonetwork B for use of the tier-2 level spectrum as compared to proposedpayments received from other networks. In another example, the selectednetwork may meet the cost condition by agreeing to payment of a set costthat is indicated in the cost condition. Upon a switch being made, thepayment may be credited by the SAS controller 104 to an accountassociated with the network B. The conditions of use may also define thetime period during which the available spectrum may be used andinformation on the frequency band and/or channels comprising thespectrum.

At 504, SAS controller 104 receives the indication of tier-2 excessspectrum availability and conditions of use from network B controller102. Processor 234 may receive the indication of tier-2 level spectrumavailability and conditions of use though network interface 228 overlink 214. Processor 234 of SAS controller 104 may process the indicationof the available spectrum and conditions of use of the spectrum alongwith information in network subscription database 236 to determine oneor more other networks of spectrum access system 100 that may utilizethe available spectrum. For example, the information in networksubscription database used in the determination may include informationas to whether particular networks at particular tier levels shouldreceive indications of available spectrum at the tier-2 level.

At 506, SAS controller 104 broadcasts an indication of the availabletier-2 level spectrum and conditions of use of the spectrum to the oneor more other networks in spectrum access system 100 as determined at504. Processor 234 may initiate the broadcast of the indication of theavailable tier-2 level spectrum and conditions of use of the spectrumthough network interface 228 on link 214 to the controllers of the oneor more other networks. For example, the controllers of the one or moreother networks may include network C controller 106 and the controllersof other networks of spectrum access system 100 not shown in FIG. 1.

At 508, SAS controller 104 receives requests for the available tier-2level spectrum and responses to conditions of use from the one or moreother networks. Processor 234 may receive the requests for the availabletier-2 level spectrum and responses to conditions of use over link 214at network interface 228.

At 510, SAS controller 104 processes the requests for the availabletier-2 level spectrum and responses to the conditions of use. In animplementation in which the conditions of use include the payment of aset cost, processor 234 may process the requests for the availabletier-2 level spectrum and responses to the conditions of use bydetermining the networks associated with the responses indicating thatthe conditions of use are acceptable. If only one network is associatedwith a response indicating that the conditions of use are acceptable,that network is chosen for the tier switch. If more than one network isassociated with a response indicating that the conditions of use areacceptable, processor 234 may chose a network for the tier switch basedon a priority. For example, network subscription database 236 may storea priority for each network of spectrum access system 100 that defineseach network's priority relative to other networks for access toavailable excess spectrum. In an implementation in which the conditionsof use include offering the highest bid for the available spectrum, anetwork that offers the highest bid for use of the spectrum as comparedto other networks to which the available spectrum is presented is chosenfor the tier switch. If no requests for the available tier-2 levelspectrum are received at 508 the broadcast may be repeated. Also, in animplementation in which the conditions of use include offering thehighest bid/payment of use for the available spectrum and two or morenetworks have offered the same highest bid, the broadcast may berepeated to those two or more networks in order that the networks maysend another bid/payment.

At 512, SAS controller 104 assigns the available tier-2 spectrum fornetwork B to the network chosen in 510. In order to implement theoperation of 512, processor 234 of SAS controller 104 may interact withnetwork tier database 232 and channel assignment database 230 to createa temporary assignment of network C to the tier-2 level for theavailable spectrum and a temporary block of network B from use of thespectrum in the tier-2 level. Processor 214 then initiates the sendingof the channel assignments to network C controller 106 over link 214through network interface 228. The channel assignments used at 512 maybe stored in network tier database and channel assignment database 230as temporary assignments that are valid for the time period of the tierswitch. Based on what the cost conditions were, processor 234 may alsoinitiate a credit to an account associated with network B, and acorresponding debit to an account associated with network C, in networksubscription database 236.

FIG. 5B is a flow diagram illustrating operations performed by anexample network controller when switching tier levels to utilizeavailable spectrum in a spectrum access system. FIG. 5B may be explainedusing SAS controller 104 and network C controller 106 of FIGS. 1 and 2Aas the network C controller and SAS controller, respectively, of FIG.5B. FIG. 5B shows how a network C controller would communicate with anSAS controller performing the process of FIG. 5A.

The process begins at 520 where network C controller 106 receives anindication of the available tier-2 level spectrum and conditions of useof the spectrum broadcast by SAS controller 104. Processor 220 mayreceive the indication of the available tier-2 level spectrum andconditions of use of the spectrum at network interface 219, and at 522,process the received indication and conditions of use. Processor 220 mayprocess the indication of the available tier-2 spectrum and theconditions of use using a cost/benefits analysis to determine if networkC may benefit from use of the available tier-2 spectrum subject to theconditions of use. For example, Processor 220 may determine that networkC may benefit from having additional bandwidth during the time periodsdefined in the condition of use based on information stored inchannel/network parameter monitor 222. Processor 220 may also determinethat that cost indicated in the conditions of use is bearable given theextent of the need for additional bandwidth during those time periodsdefined in the conditions of use. In an implementation in which theconditions of use include offering the highest bid for the availablespectrum, processor 220 may determine a bid offer based on the needduring that time period. In the example of FIG. 5B, processor 220 maydetermine that network C may benefit from use of the available spectrumsubject to the conditions of use and the process moves to 524. In analternative scenario, if processor 220 had determined that network wouldnot benefit from use of the additional spectrum subject to theconditions of use, processor 220 may end the process at 522.

At 524, network C controller 106 initiates the sending of a request forthe tier-2 level spectrum and a response to the conditions of use to SAScontroller 104. Processor 220 initiates the sending of the request onlink 214 from network interface 219. The response to the condition ofuse may include an indication of acceptance of the conditions of use,for example acceptance of a set cost or a bid for use of the tier-2level spectrum. Network C controller 106 may be one of a number ofnetwork controllers in spectrum access system 100 that have received theindication of the available tier-2 spectrum and the conditions of use,and are responding in a similar manner.

At 526, network C controller 106 determines if a request for the tier-2level spectrum and a response to the conditions of use have beenaccepted by SAS controller 104. Processor 220 may receive a response tothe request for the tier-2 level spectrum at network interface 219 onlink 214 from SAS controller 104 that indicates whether SAS controller104 has accepted the request of network C controller 106 for theavailable spectrum. If it determined that SAS controller 104 does notaccept the request, the process ends. If it is determined that SAScontroller accepts the request, the process moves to 528.

At 528, Network C controller 106 receives tier-2 channel assignments inthe available tier-2 level spectrum from SAS controller 104. Processor220 receives the channel assignments at network interface 219 on link214 identifying at least one channel that SAS controller 104 hasassigned to network C as a tier-2 level network. Channel assignmentmanager 218 processes the channel assignment and stores the identity ofthe assigned channels in a channel assignment database. Processor 220then controls channel assignment manager 218 to communicate with accesspoint 132 to allocate channels for use by access point 132.

The timing of when operation 528 takes place depends on the time periodsdefined in the conditions of use. For example, if the conditions for usedefined a particular time period of the day or week, network Ccontroller 106 would receive tier-2 channel assignments for use at thattime period.

At 530, access point 132 then operates on one or more of the channelsassigned at 528 to network C as a tier-2 level device in the spectrumswitched to network C from another network. As network C operates as atier-2 network, processor 220 of network C controller 106 may monitor atimer to determine if the time period for the tier switch according tothe conditions of use has expired. When the tier switch time periodexpires, the process moves back to 402 where network C controller 106terminates operation at the tier-2 level and initiates operation at thetier-3 level in spectrum access system 100.

FIG. 6A is a diagram illustrating an example network having devicesconfigured to switch between tier levels within the network in aspectrum access system. FIG. 6A shows network 800 that includes networkcontroller 602, access points 604, 606, 608, 610, and 612, and devices614, 616, 618, 620, 622, 624, and 626. Network 800 may bebusiness/organizational local area network (LAN) and access points604-612 may be access points that operate according to one or more Wi-Fistandards. Devices 614-626 may be any type of device that has capabilityto communicate with one or more of access points 604-612 using channelsimplemented according to the appropriate W-Fi standard. Network 600 maybe one network that is part of a larger spectrum access system thatincludes SAS controller 628.

In the implementation of FIG. 6A, SAS controller 628 may assign at leasta first tier level and/or a second tier level of priority to networks,including network 800, operating in the spectrum access system. Networkcontroller 602 may assign either the first and/or the second tier levelto each of the access points 604-612 operating in network 600.

For example, network controller 602 may receive an assignment of atleast one first channel from the SAS controller 628 and assign the atleast one first channel to access points 604 and 606 based on accesspoints 604 and 606 being assigned the first tier level by networkcontroller 602. Network controller 602 may also receive an assignment ofat least one second channel from SAS controller 628 and assign the atleast one second channel to access points 608, 610, and 612 based onaccess points 608, 610, and 612 being assigned the second tier level bynetwork controller 602. In an implementation, the priority of the secondtier level may be higher than the priority of the first tier levelwithin the spectrum access system. For example, the first and secondtier levels may be the tier-3 and tier-2 levels, respectively, of a3-tier spectrum access system controlled by SAS control 628.

During operation of network 600, network controller 602 may determinethat a tier switch between access points 604 and 606 and access points610 and 612 is to take place, i.e., is triggered. Network controller 602may initiate the tier switch by assigning access points 604 and 606 tothe second tier level and access points 610 and 612 to the first tierlevel, and assign the at least one second channel to access point 604and 605 and the at least one first channel to access points 610 and 612.In one example scenario, the controller may determine that the tierswitch between access points 604 and 606 and access points 610 and 612is to take place by determining that the at least one first channel usedby access points 604 and 606 is degraded and that, based on some networkcriteria, access points 604 and 606 should be given better qualitychannels than access points 610 and 612.

FIG. 6B is a flow diagram illustrating operations performed by anexample network controller when switching device tier levels within anetwork of a spectrum access system. FIG. 6B may be explained withreference to FIG. 6A using the example described above with SAScontroller 628 being the controller of a 3-tier level spectrum accesssystem that includes network 600 under its management.

The process begins at 630 where network controller 602 receives tier-2level and tier-3 level channel assignments from SAS controller 628. Thechannels assignments may be received in response to one or more databasequeries sent to SAS controller 628 by network controller 602. The tier-2level and tier-3 level channel assignments may assign a set of channelsat the tier-2 level and a set of channels at the tier-3 level for use bynetwork 600.

At 632, network controller 602 configures groups of access points withinnetwork 600 into tier-2 level and tier-3 level access point groups.Controller 600 may configure the groups based on the relative priorityof communications carried by each of the access points 604-612. Forexample, controller 600 may determine access points 604 and 606currently carry lower priority communications and configure accesspoints 604 and 606 as a tier-3 level access point group. Controller 600may also determine that access points 608, 610, and 612 currently carryhigher priority communications and configure access point 608, 610, and612 as a tier-2 level access point group. In an example scenario ofthis, access points 608, 610, and 612 may be installed in an executivemeeting room where important meetings often take place, while accesspoints 604 and 606 are installed in a secondary meeting room. Accesspoints 608, 610, and 612 therefore merit a higher priority tier level.

At 634, network controller 602 assigns tier-2 channels to the tier-2access point group comprising access points 608, 610, and 612 and tier-3channels to the tier-3 access point group comprising access points 604and 606.

At 636, during operation of network 600, network controller 602 monitorschannel parameters and the traffic usage/load of access points 604-612.For example, network controller 602 may monitor interference levels, biterror rates, or other parameters related to channel quality of each ofthe channels used by the individual access points 604-612. Networkcontroller 602 may receive results of measurements performed at devices614-624 and access point 604-612 to perform the monitoring. Networkcontroller 602 may also monitor throughput and traffic usage/loaddemands on each of the access points 604-612 during operation of network600.

At 638, network controller 602 determines if a tier switch is triggeredin network 600. If network controller 602 determines that a tier switchis not triggered, the process returns to 636 where controller 602continues to monitor channel parameters and the traffic usage/load ofaccess points 604-612. If network controller 602 determines that a tierswitch is triggered, the process moves to 640.

The determination at 638 of whether a tier switch is triggered may bebased on information from the monitoring performed at 434. For example,network controller 602 may determine that channel quality of the tier-3channels assigned to the tier-3 access point group comprising accesspoints 604 and 606 has degraded to below an acceptable level while thetraffic usage/load demands of access points 604 and 606 have increased.At the same time controller 602 may determine that the trafficusage/load demands on the tier-2 channels assigned to the tier-2 accesspoint group comprising access points 608, 610, and 612 have decreasedand the tier-2 channels are underutilized. Based on the relativesituations of each of the access points, network controller maydetermine that a tier switch should occur between the tier-3 accesspoint group comprising access points 604 and 606 and the tier-2 accesspoint group comprising access points 608, 610, and 612. In other words,the tier levels of the access point groups should be switched so thataccess points 604 and 606 may utilize the higher priority tier-2 levelchannels that are currently underutilized and assigned to access points608, 610, and 612.

At 640, controller 602 reconfigures the tier-2 and tier-3 access pointgroups based on the monitoring results by reconfiguring access points604 and 606 as a tier-2 level access point group and reconfiguringaccess points 608, 610, and 612 as a tier-2 level access point group.The process then moves back to 634. At 634, network controller 602assigns tier-2 channels to the tier-2 access point group comprisingaccess points 604 and 606 and tier-3 channels to the tier-3 access pointgroup comprising access points 608, 610, and 612.

The tier switching achieved by the example process of FIG. 6B may beimplemented using any type of access point group. For example, theaccess points may each be treated separately by treating each accesspoint as an access point group with one member, and the tier switchingmay be performed between individual access points rather than groups ofaccess points. Also, the tier switching may include moving individualaccess point between access point groups to switch the tier level ofindividual access points, rather than switching the tier levels of theall the access points of an access point group.

FIG. 7 is a simplified block diagram showing an example networkcontroller 700 that may be implemented in a network in a spectrum accesssystem. Network controller 700 represents an example implementation ofnetwork B controller 102 that was described in relation to FIGS. 1, 2B,and 3B. Network controller 700 may also represent an exampleimplementation of network C controller 106 that was described inrelation to FIGS. 1, 2A, and 3A.

Network controller 700 includes processor 704, network interface 714,interface to base stations/access points 702, and memory/storage 706.Memory/storage 706 includes code and program/instructions for channelassignment manager programs 708, channel/network parameter monitoringprograms 710, and tier switch timing programs 712. Network controller700 may connect though network interface 714 to a backend network thatprovides a connection to an SAS controller of a spectrum access system.Network interface 714 may be any type of interface, wireless orotherwise, to a backend network, for example the internet. Interface tobase stations/access points 702 may be any type of interface, wirelessor otherwise, that allows network controller 700 to communicate withbase stations and/or access points such as base stations 122 and 126,and access point 132 of FIG. 1A.

Processor 704 may comprise one or more processors, or other controlcircuitry or any combination of processors and control circuitry thatprovide overall control of network controller 700 according to thedisclosed embodiments. Memory 706 may be implemented as any type of asany type of computer readable storage media, including non-volatile andvolatile memory.

In an implementation, execution of channel assignment manager programs708, channel/network parameter monitoring programs 710, and tier switchtimer 712 causes processor 704 to implement operations that causenetwork controller 700 to operate according to the operations describedfor network controllers 102 and 106 in relation to the implementationsdescribed in this disclosure.

FIG. 8 is a simplified block diagram showing an SAS controller 800 thatmay be implemented in a spectrum access system. SAS controller 800represents an example implementation of SAS controller 104 that wasdescribed in relation to FIGS. 1, 3C, 5A and 6B. Base station 800includes processor 804, network interface 802, and memory/storage 806that includes code and program/instructions for network channelassignment programs 808, channel assignment database 810, devicetier/subscription database 812, and tier switch manager/databaseprograms 814. SAS controller may connect to one or more networkcontrollers, such as network controllers 102 and 105 of FIG. 1, throughnetwork interface 802. Network interface 802 may be any type ofinterface, wireless or otherwise, to a network, for example theinternet. Processor 804 may comprise one or more processors, or othercontrol circuitry or any combination of processors and control circuitrythat provide overall control of SAS controller 800 according to thedisclosed embodiments. Memory 806 may be implemented as any type of asany type of computer readable storage media, including non-volatile andvolatile memory.

In an implementation, execution of network channel assignment programs808 and tier switch manager/database programs 814, in conjunction withchannel assignment database 810 and device tier/subscription database812, causes processor 804 to implement operations that cause SAScontroller 800 to operate according to the operations described for SAScontroller 104 in relation to the implementations of this disclosure.

The example embodiments disclosed herein may be described in the generalcontext of processor-executable code or instructions stored on memorythat may comprise one or more computer readable storage media (e.g.,tangible non-transitory computer-readable storage media such as memory706 or 806). As should be readily understood, the terms“computer-readable storage media” or “non-transitory computer-readablemedia” include the media for storing of data, code and programinstructions, such as memory 706 or 806, and do not include portions ofthe media for storing transitory propagated or modulated datacommunication multi-carrier signals.

While the functionality disclosed herein has been described byillustrative example using descriptions of the various components anddevices of embodiments by referring to functional blocks and processorsor processing units, controllers, and memory including instructions andcode, the functions and processes of the embodiments may be implementedand performed using any type of processor, circuit, circuitry orcombinations of processors and/or circuitry and code. This may include,at least in part, one or more hardware logic components. For example,and without limitation, illustrative types of hardware logic componentsthat can be used include field programmable gate arrays (FPGAs),application specific integrated circuits (ASICs), application specificstandard products (ASSPs), system-on-a-chip systems (SOCs), complexprogrammable logic devices (CPLDs), etc. Use of the term processor orprocessing unit in this disclosure is mean to include all suchimplementations.

The disclosed implementations include a controller for controlling afirst and a second network in a spectrum access system having aplurality of tier levels for spectrum access. The controller comprisedone or more processors and memory in communication with the one or moreprocessors. The memory comprises code that, when executed, causes theone or more processors to control the controller to assign one or morefirst channels to a first network based on the first network beingassigned a first tier level of the plurality of tier levels, determinethat a tier switch is to take place between the first network and asecond network assigned a second tier level of the plurality of tierlevels, initiate the tier switch between the first network and thesecond network, and, assign, in response to the determination that thetier switch is to take place, one or more second channels to the secondnetwork based on the second network being assigned the first tier level.The controller may further assign, in response to the determination thatthe tier switch is to take place, one or more third channels to thefirst network based on the first network being assigned the second tierlevel. The code may further cause the controller to receive a tierswitch request from the first network and determine that the tier switchis to take place based on the tier switch request. The code may furthercauses the controller to receive a tier switch request from the firstnetwork, send a tier switch query to the second network based on thetier switch request, receive a response from the second network, and,determine that the tier switch is to take place based on the responsefrom the second network. The controller may determine that the tierswitch is to take place between the first network and the second networkfor the duration of a tier switch period, and assigns the one or moresecond channels to the second network for the duration of the tierswitch period. The second tier level may be a tier-1 level of a threetier spectrum access system or the second tier level may be a tier-2level of a three tier spectrum access system.

The disclosed implementations also include a controller for a network ina spectrum access system having a plurality of tier levels for spectrumaccess priority. The controller comprises one or more processors andmemory in communication with the one or more processors. The memorycomprises code that, when executed, causes the one or more processors tocontrol the controller to receive an assignment of at least one firstchannel based on the network being assigned a first tier level of theplurality of tier levels by the spectrum access system, monitor aparameter of the network, determine that a switch to a second tier levelof the plurality of tier levels is to take place based at least on theparameter, send an indication to the spectrum access system that thenetwork is switching to the second tier level of the plurality of tierlevels, and, initiate operation of the network on at least one secondchannel based on the network being assigned the second tier level of theplurality of tier levels by the spectrum access system. The controllermay determine that the switch to the second tier level of the pluralityof tier levels is to take place based at least on the parameter and acost function. The controller determines that the tier switch to thesecond tier level is to take place for the duration of a time period,and control the network to operate on the at least one second channelbased on the network having the second tier level during duration of thetime period. The parameter may include a parameter on a selected channelof the at least one rust channel.

The disclosed implementations also include a controller for controllingdevices in a network within a spectrum access system having at least afirst tier level and a second tier level of priority for spectrumaccess. The controller comprises one or more processors and memory incommunication with the one or more processors. The memory comprises codethat, when executed, causes the one or more processors to control thecontroller to receive an assignment of at least first channel from thespectrum access system and assign the at least one first channel to atleast one first device based on the at least one first device beingassigned the first tier level in the network, assign at least one secondchannel to at least one second device based on the at least one seconddevice being assigned the second tier level in the network, determinethat a tier switch between the at least one first device and the atleast one second device is to take place, initiate a tier switch betweenthe at least one first device and at least one second device, and,assign the at least one second channel to the at least one first deviceand the at least one first channel to the at least one second device.The controller may further receive an assignment of the at least onesecond channel from the spectrum access system. The second tier levelmay be a highest priority level of the spectrum access system. Thepriority of the first tier level may be lower than the priority of thesecond tier level, and the controller may determines that a tier switchbetween the at least one first device and the at least one second deviceis to take place by determining that the quality of the at least onefirst channel is degraded.

The disclosed implementations further include a controller forcontrolling a plurality of networks in a spectrum access system havingat least first and second tier levels for spectrum access. Thecontroller comprises one or more processors and memory in communicationwith the one or more processors. The memory comprises code that, whenexecuted, causes the one or more processors to control the controller toreceive information on first tier level spectrum available for use byone or more second networks from a first network, wherein the firstnetwork is operating at the first tier level, send the information onthe first tier level spectrum to the one or more second networks,receive at least one response from the one or more second networks,process the at least one response, and, assign one or more channels ofthe first tier level spectrum to a selected network of the one or moresecond networks based on the at least one response. The information onthe first tier level spectrum may include conditions of use for thefirst tier level spectrum. The conditions of use may include a costcondition and the at least one response may indicate that the selectednetwork of the one or more second networks accepts the cost condition.The conditions of use may include responding with a highest proposedpayment, and the at least one response may indicate that the selectednetwork of the one or more second networks has responded with thehighest proposed payment. The conditions of use may include a timeperiod during which the first tier level spectrum is available.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample embodiments, implementations, and forms of implementing theclaims and these example configurations and arrangements may be changedsignificantly without departing from the scope of the presentdisclosure. Moreover, although the example embodiments have beenillustrated with reference to particular elements and operations thatfacilitate the processes, these elements, and operations may be combinedwith or, be replaced by, any suitable devices, components, architectureor process that achieves the intended functionality of the embodiment.Numerous other changes, substitutions, variations, alterations, andmodifications may be ascertained to one skilled in the art and it isintended that the present disclosure encompass all such changes,substitutions, variations, alterations, and modifications as fallingwithin the scope of the appended claims.

What is claimed is:
 1. A controller for controlling a first and a secondnetwork in a spectrum access system having a plurality of tier levelsfor spectrum access, the controller comprising: one or more processors;and, memory in communication with the one or more processors, the memorycomprising code that, when executed, causes the one or more processorsto control the controller to: assign one or more first channels to thefirst network based on the first network being assigned a first tierlevel of the plurality of tier levels; determine that a tier switch isto take place between the first network and the second network, whereinthe second network is assigned a second tier level of the plurality oftier levels; initiate the tier switch between the first network and thesecond network; and, assign, in response to the determination that thetier switch is to take place, one or more second channels to the secondnetwork based on the second network being assigned the first tier level.2. The controller of claim 1, wherein the controller further assigns, inresponse to the determination that the tier switch is to take place, oneor more third channels to the first network based on the first networkbeing assigned the second tier level.
 3. The controller of claim 1,wherein the code further causes the controller to: receive a tier switchrequest from the first network; and, determine that the tier switch isto take place based on the tier switch request.
 4. The controller ofclaim 1, wherein the code further causes the controller to: receive atier switch request from the first network; send a tier switch query tothe second network based on the tier switch request; receive a responsefrom the second network; and, determine that the tier switch is to takeplace based on the response from the second network.
 5. The controllerof claim 1, wherein the controller determines that the tier switch is totake place between the first network and the second network for theduration of a time period, and assigns the one or more second channelsto the second network for the time period.
 6. The controller of claim 1,wherein the second tier level is a tier-1 level of a three tier spectrumaccess system.
 7. The controller of claim 1, wherein the second tierlevel is a tier-2 level of a three tier spectrum access system.
 8. Acontroller for a network in a spectrum access system having a pluralityof tier levels for spectrum access priority, the controller comprising:one or more processors; and, memory in communication with the one ormore processors, the memory comprising code that, when executed, causesthe one or more processors to control the controller to: receive anassignment of at least one first channel based on the network beingassigned a first tier level of the plurality of tier levels by thespectrum access system; monitor a parameter in the network; determinethat a switch to a second tier level of the plurality of tier levels isto take place based at least on the parameter; send an indication to thespectrum access system that the network is switching to the second tierlevel of the plurality of tier levels; and, initiate operation of thenetwork on at least one second channel based on the network beingassigned the second tier level of the plurality of tier levels by thespectrum access system.
 9. The controller of claim 8, wherein thecontroller determines that the switch to the second tier level of theplurality of tier levels is to take place based at least on theparameter and a cost function.
 10. The controller of claim 8, whereinthe controller determines that the tier switch to the second tier levelis to take place for a time period, and controls the network to operateon the at least one second channel during the time period.
 11. Thecontroller of claim 8, wherein the parameter is a parameter measured ona selected channel of the at least one first channel.
 12. A controllerfor controlling devices in a network within a spectrum access systemhaving at least a first tier level and a second tier level of priorityfor spectrum access, the controller comprising: one or more processors;and, memory in communication with the one or more processors, the memorycomprising code that, when executed, causes the one or more processorsto control the controller to: receive an assignment of at least a firstchannel from the spectrum access system and assign the at least onefirst channel to at least one first device based on the at least onefirst device being assigned the first tier level in the network; assignat least one second channel to at least one second device based on theat least one second device being assigned the second tier level in thenetwork; determine that a tier switch between the at least one firstdevice and the at least one second device has been triggered; initiate atier switch between the at least one first device and the at least onesecond device; and, assign the at least one second channel to the atleast one first device and the at least one first channel to the atleast one second device.
 13. The controller of claim 12, wherein the oneor more processors further control the controller to receive anassignment of the at least one second channel from the spectrum accesssystem.
 14. The controller of claim 12, wherein the second tier level isa highest priority level of the spectrum access system.
 15. Thecontroller of claim 12, wherein the priority of the first tier level islower than the priority of the second tier level, and wherein thecontroller determines that a tier switch between the at least one firstdevice and the at least one second device is triggered by determiningthat the quality of the at least one first channel is below a threshold.16. A controller for controlling a plurality of networks in a spectrumaccess system having at least first and second tier levels for spectrumaccess, the controller comprising: one or more processors; and, memoryin communication with the one or more processors, the memory comprisingcode that, when executed, causes the one or more processors to controlthe controller to: receive information from a first network on firsttier level spectrum available for use by one or more second networks,wherein the first network is operating at the first tier level; send theinformation on the first tier level spectrum to the one or more secondnetworks; receive at least one response from the one or more secondnetworks; process the at least one response; and, assign one or morechannels of the first tier level spectrum to a selected network of theone or more second networks based on the at least one response.
 17. Thecontroller of claim 16, wherein the information on the first tier levelspectrum includes conditions of use for the first tier level spectrum.18. The controller of claim 17, wherein the conditions of use includes acost condition and the at least one response indicates that the selectednetwork of the one or more second networks accepts the cost condition.19. The controller of claim 17, wherein the conditions of use includesresponding with a highest bid, and the at least one response indicatesthat the selected network of the one or more second networks hasresponded with the highest bid.
 20. The controller of claim 17, whereinthe conditions of use includes a time period during which the first tierlevel spectrum is available.